Channel-type carbon black process



United States Patent M 3,039,853 CHANNEL-TYPE CARBON BLACK PROCESS Joe Y. Rogers, Jr., and John M. Brown, Pampa, Tex., assignors to Cabot Corporation, Boston, Mass., at corporation of Delaware No Drawing. Filed Mar. 18, 1960, Ser. No. 15,848 7 Claims. (Cl. 23-2093) This invention rel-ates to the production of carbon black by the impingement of a hydrocarbon flame against a relatively cool surface, for example the channel process, and in particular to an improved process for producing high color channel carbon black.

In the production of high color (i.e. having a nigrometer scale reading of below about 82) channel carbon black, a diluent, such as air, nitrogen or carbon dioxide, is generally added to the natural gas feed stock. Also in recent years, in order to enrich the gas and increase the production rate of carbon black, a hydrocarbon such as a hydrocarbon oil is often vaporized into the natural gas feed stream, for example as taught by US. Patent 2,719,078, to Billings and Darwin. When either a diluent or a hydrocarbon alone is added to the natural gas, serious problems do not arise. When, however, a diluent and a hydrocarbon are both added to the natural gas feed stream, flame forking and, ultimately, blocking of the burner tips occurs. Flame forking may be described as the change in the pattern of the flame emanating from the btuner tip which occurs when a coke-like material deposits at the burner tip and forms an obstruction therein which deflects the gases emanating from said tip and thereby causes the flame to separate into two or more forks. Much research has been conducted to determine the cause of flame forking. Various factors including the possible oxidation and polymerization of the hydrocarbon as described in copending application Serial No. 689,330, to

Rogers et al., now Patent No. 2,981,604, and the temperature of the system, were investigated, but no completely practical and inexpensive solution to the problem of flame forking had heretofore been discovered. The present invention, however, offers a more complete and less expensive solution to said flame forking problem.

Accordingly, it is a principal object of the present invention to provide an improved process for producing high color impingement type carbon black from artificially enriched gases such as natural gas.

Another object of this invention is to provide a process for preventing flame forking in the production of high color channel carbon blacks when the feed stock comprises natural gas, an enriching hydrocarbon and a diluent such as air, molecular oxygen, carbon dioxide, nitrogen, water vapor, etc.

Another object of this invention is to provide a process for preventing flame forking in the production of high color channel carbon blacks when the feed stock comprises natural gas, a hydrocarbon oil and air.

Other objects will in part be obvious and will in part appear hereinafter.

In accordance with the present invention, it was discovered that in producing high color channel carbon black from a feed stock comprising diluted natural gas enriched with a normally liquid hydrocarbon, flame forking is prevented by cleansing the diluent of solid materials prior to its introduction itno the feed stock. The problem is complex and it is not completely understood why cleansing of the diluent prevents flame forking, but it is believed, and there is no intention to be bound by this explanation, that the dust, smoke, and other solid, particulate contaminants normally present in a diluent, such as air, tend to be agglomerated at the burner tip by some of 3,039,853 Patented June 19, 1962 the higher boiling portions of the hydrocarbon, and/or by polymerization of certain fractions of the hydrocarbon. Agglomerates then build up to form coke-like deposits which restrict the opening in the burner tip thereby causing flame forking and ultimately blocking of the burner tips.

The degree of improvement achieved by the present invention is, of course, for a given feed stock, largely dependent upon the completeness of removal of the solid materials. Flame forking can be almost entirely eliminated by filtering the diluent to the point where substantially no solid particulate material remains therein. If filtration of the diluent is carried out to a lesser extent, flame forking will occur over a period of time, the length of said period being determined by the extent of filtration.

Any type of filter or filtering system which will reduce or completely eliminate the solid content of the diluent is suitable for the purposes of the present invention. For example, bag filters such as of Fiberglas or Orlon, oilbath air filters, Cottrell precipitators or wet scrubbers are all useful for the purposes of the present invention.

Any normally liquid hydrocarbon is generally suitable for enrichment of the natural gas. However, hydrocarbon oils or blends of hydrocarbon oils having a distillation end point of less than about 900 F. are generally preferred.

Also, the diluent-natural gas hydrocarbon ratios are not critical for the purposes of the present invention. Suitable ratios for producing the various grades of carbon black are well known in the channel carbon black industry and moreover do not basically alter the results and advantages of the present invention.

There follow a number of non-limiting illustrative examples:

Example 1 To a typical channel carbon black building comprising a 140-200 ft. long hot house equipped with about 3000 burner tips arranged in longitudinal rows, and a channel member suspended over each row of burner tips, there was fed 230 M c.f.d. (thousand cubic feet corrected to 60 F. and 30 mercury pressure, per day) natural gas, M c.f.d. of unfiltered air and about 6 gallons per hour of a distillate oil having a distillation end point of about 654 F. and which contained by weight 53.3% aromatics, 8.9% olefins and 37.8% saturates, and which had an A.P.I. gravity of 28.1 and a US. Bureau of Mines correlation index of 54.4. Normal operation was maintained for about 12 hours, after which time flame forking was first observed in some of the burner tips. 16 hours after the initiation of the run, flame forking was generally prevalent throughout the hot house.

Example 2 This example was a duplicate of Example 1, except that the 110 M c.f.d. air was filtered by means of a bag filter consisting of three porous filter bags, each about 5 inches in diameter and about 5 feet long, prior to being utilized. After 3 /2 weeks of operation, no flame forking had been observed.

Example 3 This example was a duplicate of Example 1, except that instead of the distillate oil described in Example 1, 7.5 gallons per hour of kerosene were utilized. Normal operation was maintained for about 2 /2 months, after which time flame forking was becoming general.

Example 4 This example was a duplicate of Example 3, except that the 110 M c.f.d. air was filtered by means of a bag filter consisting of 3 porous filter bags each about 5 inches ingly filtration of the natural gas is usually unnecessary. 10

Also, of course, instead of filtering the diluent prior to adding it to the natural gas, the diluent and natural gas could be first admixed and the entire mixture subsequently filtered. However, this procedure would normally require filtering equipment of higher capacity and would 15 therefore be unnecessarily costly.

It is therefore, intended that the above description and examples =be viewed as illustrative and as in no way limiting the scope of the present invention.

What we claim is: 20

1. In the process of producing high color carbon black by the channel process wherein a mixture comprising natural gas, a diluent and a normally liquid hydrocarbon is burned under conditions of incomplete combustion, the

improvement which comprises ridding said diluent of solid 25 materials prior to the addition thereof to the other components.

' 2. The process of claim 1 wherein said hydrocarbon comprises a hydrocarbon oil having a distillation end point of less than about 900 F.

3. The process of claim 1 wherein said hydrocarbon comprises a blend of hydrocarbon oils.

4. The process of claim 1 wherein said diluent comprises air.

5. The process of claim 1 wherein said diluent is filtered to the point wherein only trace amounts of solid matter remain therein.

6. In the process of producing high color carbon black by the channel process wherein a mixture comprising natural gas, air and a hydrocarbon oil is burned under conditions of incomplete combustion, the improvement which comprises filtering said air by means of a bag filter prior to the mixing of said air with the other components.

7. In a process for producing high color carbon black by the channel process wherein a mixture comprising natural gas, a diluent and a normally liquid hydrocarbon is burned under conditions of incomplete combustion, the improvement which comprises ridding said diluent and said natural gas of solid materials prior to the mixing thereof with said liquid hydrocarbon.

References Cited in the file of this patent UNITED STATES PATENTS 2,225,354 Schmalenbach Dec. 17, 1940 2,307,050 Kloepfer Jan. 5, 1943 2,719,078 Billings et a1 Sept. 27, 1955 

1. IN THE PROCESS OF PRODUCING HIGH COLOR CARBON BLACK BY THE CHANNEL PROCESS WHEREIN A MIXTURE COMPRISING NATURAL GAS, A DILUENT AND A NORMALLY LIQUID HYDROCARBON IS BURNED UNDER CONDITIONS OF IMCOMPLETE COMBUSTION, THE IMPROVEMENT WHICH COMPRISES RIDDING SAID DILUENT OF SOLID MATERIALS PRIOR TO THE ADDITION THEREOF TO THE OTHER COMPONENTS. 